66 replies to this topic

[vic2003 TT Bronze Member]

If you guys haven’t signed the two stoke petition already I would encourage you do so. It only takes two minutes to complete and it shows interest for two strokes in pro racing. There has already been dialog between the petition starter and the AMA. Link to petition below.

http://www.gopetitio...ule-change.html

http://twostrokemoto...troke-petition/

http://blogs.dirtrid...roke/index.html

[Sycamore TT Bronze Member]

I dont get it. Why are they asking for 100cc-150cc in the 250 class? Why not 250cc in the 250cc? And why not up to 450cc in the 450 class?

[dandm95 TT Bronze Member]

Sycamore said:

I dont get it. Why are they asking for 100cc-150cc in the 250 class? Why not 250cc in the 250cc? And why not up to 450cc in the 450 class?

Because that would be embarrassing for all the valve eaters. :lol:

Too much factory money involved to create that kind of playing field...

Signed it.

Edited by dandm95, 06 August 2010 - 09:27 AM.

[vic2003 TT Bronze Member]

Sycamore said:

I dont get it. Why are they asking for 100cc-150cc in the 250 class? Why not 250cc in the 250cc? And why not up to 450cc in the 450 class?

My guess is because it would never pass. We all know how the manufactures (Honda) would never let this happen.

[Romster TT Silver Member]

This is a step in the right direction. As soon as DI 2 strokes come out, 4 strokes will be obsolete. Mark my words.

Signed btw.

[mbaird TT Bronze Member]

a 2t of equal cc's makes more power and torque assuming the 4t is not NO2ed,turboed or supercharged . But there will still be a place for 4t's because of the gyroscopic effect of all that rotating mass .
If I were a desert racer a 4t would be the way to go , but in the mtn's and tight stuff 2t is the way to go . IMO

[jebova2301 TT Bronze Member]

Sycamore said:

I dont get it. Why are they asking for 100cc-150cc in the 250 class? Why not 250cc in the 250cc? And why not up to 450cc in the 450 class?

stop asking for everything. look at it this way. right now, 2 strokes have nothing. i would sure rather have at least SOMETHING in there. that means we get the trickle down from it. even if we cant get things to be perfect, at least getting 2 strokes back in means we have got a foot in the door.

signed btw

[Romster TT Silver Member]

mbaird said:

a 2t of equal cc's makes more power and torque assuming the 4t is not NO2ed,turboed or supercharged . But there will still be a place for 4t's because of the gyroscopic effect of all that rotating mass .
If I were a desert racer a 4t would be the way to go , but in the mtn's and tight stuff 2t is the way to go . IMO

You are right, if we are talking current 2 strokes that are available. But it is also true that you can make a 2 stroke engine feel like a 4 stroke, it has been done before. You can add weight and rotating mass (flywheel) to a 2 stroke, as well as change ignition timing and power valve springs, but you cannot subtract weight from a 4 stroke. Also, like I said before, DI 2 stroke will change everything you think about 2 strokes.

[Micahdogg TT Silver Member]

I signed. And if direct injection comes along, 150cc will be MORE than enough for a typical 250F.

[40oz]

Good cause. Is now a sticky for a while.

[ossidog]

mbaird said:

a 2t of equal cc's makes more power and torque assuming the 4t is not NO2ed,turboed or supercharged . But there will still be a place for 4t's because of the gyroscopic effect of all that rotating mass .
If I were a desert racer a 4t would be the way to go , but in the mtn's and tight stuff 2t is the way to go . IMO

I concur and would like to add a paraphrase from the Yamaha Motor
designer, the maker of the first high output 4t.

A modern 4t has 0.12 HP per cc
A modern 2t has 0.2 HP per cc

Some basic math shows how the 4t has the edge. I
have a YZ 265 2t and have swapped to and from
a YZ 450 4t. There is no way it out pulls me but
in the desert give me the 450, here in the hills I
would much rather use a 2t. Good post.:ride:

[dirtbeater TT Titanium Member]

Signed

[HighRevz TT Silver Member]

Done! :thumbsup:

[Micahdogg TT Silver Member]

ossidog said:

I concur and would like to add a paraphrase from the Yamaha Motor
designer, the maker of the first high output 4t.

A modern 4t has 0.12 HP per cc
A modern 2t has 0.2 HP per cc

Some basic math shows how the 4t has the edge. I
have a YZ 265 2t and have swapped to and from
a YZ 450 4t. There is no way it out pulls me but
in the desert give me the 450, here in the hills I
would much rather use a 2t. Good post.:ride:

That math doesn't seem to work very good for a 125 2t or a 250F. Those are both right around 37 RWHP. Actually, I think the KTM125's are narrowly making more peak power than any 250F.

[MARKS300MXC TT Member]

Eventually it will happen. The industry is dying because they produced a product that is becoming unaffordable for your casual (most of us) rider. Two smokes survive because they are easy to work on, fun, and easy to ride. I have always owned two strokes and will forever. KTM and Yamaha have decided to "keep hope alive" and still continue to make what is in the consumers best interest not the manufactures. I own both a KTM and Yamaha 2sk and will continue to support both companies and disregard the manufactures who have turned their back on me, the consumer.

Two stroke for life!

[OlleR TT Bronze Member]

ossidog said:

I concur and would like to add a paraphrase from the Yamaha Motor
designer, the maker of the first high output 4t.

A modern 4t has 0.12 HP per cc
A modern 2t has 0.2 HP per cc

Some basic math shows how the 4t has the edge. I
have a YZ 265 2t and have swapped to and from
a YZ 450 4t. There is no way it out pulls me but
in the desert give me the 450, here in the hills I
would much rather use a 2t. Good post.:ride:

Its not very difficult to understand why the twostroke makes "twice" the power, since it actually fires twice the amount of times in the same revs. More or less if you get the twostroke to rev as much as the fourstroke it will make almost twice the power. Todays 250F's rev higher tho, hence the need of bigger cc's...

People often say that the fourstrokes has more torque which also is incorrect. The torque values are also "doubled". And if we look at the power curves they arent that much different either, not if you look on engines like the KTM's

I was actually impressed by my 200 SX the other day when we practiced starts, it won 12 out of 15 starts and that was vs 250 2t, 250 4t and 450 4t

No matter how you twist and turn it tho, the 4t is much easier to ride and if you try out two bikes that you have never ridden before, one 2t and one 4t, you will be much faster on the fourstroke...

[40oz]

OlleR said:

No matter how you twist and turn it tho, the 4t is much easier to ride and if you try out two bikes that you have never ridden before, one 2t and one 4t, you will be much faster on the fourstroke...

Must say, I have to personally disagree with that statement. I have owned and ridden many different bikes. The 2t for me always wins - it comes to to each person and the way they ride, their needed ergo's, etc etc. For some the 4t will win out, good thing we all have choices in motors, sizes, styles, applications, etc. :ride:

[jebova2301 TT Bronze Member]

to me, 2t is easier to ride. the first thing i ever rode was a 600cc sportbike. then i did the msf course on a tw200 and hated it. i got a little yz80 to putt around on, and fell in love with the power delivery of a 2t. now i have a 250 2t and love every bit of it. i tried riding a friends 450 4t and couldnt get the feel for it. i didnt like the way it felt heavier, didnt seem nimble, and didnt rev up as quick. granted, it had more torque, but i wasnt really fond of it

[Rider4Life_JJG TT Newbie]

Signed!

[thumpinyami59 TT Bronze Member]

MARKS300MXC said:

Two stroke for life!

I agree. I bought a two stroke a few years ago because all my friends had one and I rode it and liked it. Then I rode it for 3 months and put into the motor what I paid for it. then sold it for what I paid for it. I bought a KTM 125sx during the motor rebuild and never looked back.

Four strokes are easy to ride because the bottom end grunt(125 2st v 250 4st) makes it easier to roll on throttle out of turns etc. However I love the power my 125 has and am trying to convert it to a 200.

Also, I am a certified Evinrude tech. The E-TEC motor is a direct injected multi- cylinder two stroke. I know the injectors on this motor can support atleast 10,000 RPM and I believe I was told around 80 HP... per injector. If they had a good single cylinder setup, I would love to get a head machined for an injector and try my luck at building a Ktm ETEC. E-TEC's are 3 star EPA rated. Some four stroke marine engines still don;t have that rating.